Cylinder pressure forming paper machine with white water recovery



P 1968 M. B. KELLER 3,401,080

CYLINDER PRESSURE FORMING PAPER MACHINE WITH WHITE WATER RECOVERY Filed 001$. 15, 1965 5 Sheets-Sheet 1 INVENTOR. MARTIN B. KELLER ATTORNEY.

M. B. KELLER Sept. 10, 1968 CYLINDER PRESSURE FORMING PAPER MACHINE WITH WHITE WATER RECOVERY '3 Sheets-Sheet 2 Filed Oct. 15, 1965 INVENTOR.

MARTIN B. KELLER ATTORNEY.

Sept. 10', 1968 M. B. KELLER 3,401,080

CYLINDER PRESSURE FORMING PAPER MACHINE WITH WHITE WATER RECOVERY Filed Oct. 15, 1965 5 Sheets$heet 3 INVENTOR. MARTIN B. KELLER BY @wmw ATTORNEY.

United States Patent 3,401,080 CYLINDER PRESSURE FORMING PAPER MA- CHINE WITH WHITE WATER RECOVERY Martin B. Keller, Hudson Falls, N.Y., assiguor to Sandy Hill Corporation, Hudson Falls, N.Y. Filed Oct. 15, 1965, Ser. No. 496,302 6 Claims. (Cl. 162-264) The invention relates broadly to structural refinements in the art of papermaking and is especially directed to improved means in adjustable dry vat arrangements for producing level basis weight products.

Herein is taught, in combination, a variable stock inlet or approach flow or stock delivery mechanism for selectively delivering a variable flow of an aqueous suspension of papermaking fibers to, and the deposition of a felted web upon, a controllable web forming surface length of a rotating cylinder mold, and means for depositing the formed felted web upon a pickup felt running adjacent the top of the mold, with the obvious advantages that the web is permitted to be formed upon the mold face, dewetted through the mold, and picked up from the mold surface as by a pickup felt trained over and coacting with a couch roll mounted in nip-defining relation with the mold, the formed web being then carried tangentially away from the mold to a distant transfer point, all being accomplished with a cooperant dry vat wherein the mat of fibers is applied to the mold, as by flowing stock thereon and, through which mold the stock is allowed to drain,

the stock so applied containing the required amount of fiber in an amount of water sufficient to produce a proper distribution of fibers in a formed coherent web, and the drainage being effected during a time period commencing with the moment of contact of the mold surface with the stock supply and terminating with the moment of couching, said drainage being withdrawn through the vat on the dry side thereof to a fan pump with excesses thereof being flowed into side pocket arrangements including adjustable dam devices for raising the white water level Within the vat and ultimately inside of the mold for reducing the differential in the hydrostatic head.

In cylinder machines, the two types most commonly used are the directfiow and counterfiow types. In the directfiow type, stock is supplied to the downturning side of the mold rotating within the vat to flow undirectionally therewith. In the counterflow type, stock is fed to the upturning side of the mold to flow in a direction opposite thereto. In both types, the mold is immersed in a pond of liquid containing suspended paper fibers therein.

The directflow type is suited to produce a lighter weight of paper and usually employs stock of low consistency, the stock volume normally being large to provide a large overfiow for recirculation, and the drainage through the clean wire being high as the wire first comes into contact with the stock. The weight does not build up rapidly because of the low stock consistency. The suspended fines pass easily through the wire, only the long fibers being retained thereupon. Examination of a tight and compact ply reveals that the layer next to the wire is built up mainly of the long fibers. After formation of the first layer, the drainage rate decreases and the long fibers trap some of the fines, thereby slowly to increase the basis weight. As the Web becomes more dense, water can still pass through, yet more fibers cannot so that the sheet no longer gains weight. The loss of the water without the deposition of fibers results in an increase in consistency at the discharge side of the vat. At the area where the mold leaves the stock, the stock has a greater consistency than the V 3,401,080 Patented Sept. 10, 1968 The counterflow type, in contradistinction, is suited to form relatively heavy sheets at relatively low speeds. Stock of higher consistency is fed to the upturning side of the mold and continues to flow in a direction opposite to the direction of mold rotation. Recirculation is not normally necessary. Some fractionation ensues, but the point where the stock has highest freeness and greatest consistency is that area where the wire meets the stock on the downward pass. Because of higher freeness and greater consistency, initial deposit is great, and therefollowing, build-up continues at a relatively rapid rate with an ever-increasing amount of fines being deposited in the Web so that a stationary state is soon reached, the force necessary to continue drainage through the web being no longer attainable and the fiber layer remaining the same. As the web reaches the inlet area, it is subjected to largest flow, with the disadvantage that flow irregularities disturb the already-formed ply, wherefor preferentially, the formed web is caused to emerge from the stock immediately upon attaining the desired thickness.

In both types, the mold is immersed in a pond of liquid, which pond is continuously supplied at a rate which will maintain the pond level against the mold at a desired elevation. The liquid or white water within the mold flows outwardly through the opposite ends thereof to create a gradient from the center of the mold to the ends.

Drainage from the pond into the mold is related to the difference between the pond level and the level within the mold, the amount of liquid flowing from the pond into the mold varying from point to point across the machine width. This difference in rate of flow frequently causes a corresponding difference in the weight of the web formed on the mold surface from point to point across the mold face, a condition described by reference to the basis weight profile, a plot of basis weight measurements taken in series across the web width.

Another inherent problem lies in the fact that, for many purposes, the forming length of a mold is greater than is required to form a web of a desired weight, particularly in an instance where the cross machine width is relatively great and a large mold diameter is dictated for structural reasons. In such case, the sheet is formed in the weight required and subsequent drainage of liquid takes place through the formed web as it moves peripherally on the mold through the pond. This drainage is not of sufiicient volume or velocity to hold the suspended fibers against the already-formed web so that, as a result, fibers are Washed from the formed web and mingle in the balance of the liquid in the pond to cause a thickening of the liquid as the web proceeds around the vat circle from the initial forming area. Such thickening is detrimental to the uniformity of the formation occurring on the mold surface and to overcome the problem, it has been known to use relatively low stock consistencies meaning greater gallonages supplied to the vat per pound of fiber delivered and consequent increases in pumping horsepower.

The dry vat, as it has evolved, is a modification of the conventional counterfiow vat in the respect that formation occurs only on the upturning side of the vat.

It has been thought that the basic factor contributing to the lack of uniformity in most counter-flow vats is the initial deposit of an excess of fibers onto the cylinder face on the down-turning side of the vat, followed by an uneven washing-off action caused by the incoming stock on the up-turning side of the vat. The avoidance of such washing-off can be realized by limiting the forming area to only the upturning side of the vat, a restriction achieved by the installation of a horizontal seal extending across the vat circle at about 7 oclock so as to form a seal with the face of the cylinder. Hence the dry vat, which claims for some of the benefits obtained therewith:

(1) Improved cross-machine basis weight profile.

(2) Improved web formation.

(3) Reduced wet streaking with subsequent drying improvement.

(4) Easier vat operation and quicker responses on grade and Weight changes.

(5) Modest increases in burs-t strength.

In the herein taught invention, the vat is dry in the respects that the mold is not immersed in the stock and liquid flow from the mold takes place through the peripheral surface thereof.

Here, means are provided for adjusting a throat or approach passage relative to the headbox within which the means is disposed, wherefore the approach passage to the forming surface of the mold may be selectively controlled so as to accommodate to specific applications and in order to obtain better squareness of the sheet.

Additionally, the herein-provided structural arrangement teaches a combination of a cylinder mold rotatably suspended in a vat, curvate means radially spaced from the cylinder mold and defining cooperantly therewith a stock flow channel or approach passage, means for adjusting the curvate means for essentially restricting the channel, means for discharging the stock flow through the channel whereby fibers thereof are deposited on the cylinder mold at one side thereof and liquid thereof flows into the mold and through the opposite side thereof and into the vat and thence into novel side pockets at opposite sides of the apparatus.

Inasmuch as the forming length is not defined by any depth of immersion of the mold in the pond, the problems of fiber washotf and thickening of slurry are eliminated. Thickening being greatly minimized, higher consistencies can accordingly be utilized. This further results in a lower gallonage per pound of delivered fiber being supplied to the vat, with a consequent marked saving in pumping horsepower.

As another object hereof, I provide means for controlling the velocity relationships of the stock preliminary to arrival at the web-forming region. A flow distributor component converts a fast flowing stock stream of relatively small cross-section to a slow flowing stock stream of relatively large cross-section by passage thereof from a manifold inlet to an inlet header, and then by a right angle turn into a fast flowing stock stream by passage through a primary approach or turbulence chamber in th form of a restricted throat, and then by another right angle turn into a slow flowing stock stream by passage through a secondary approach chamber preparatory to entry into the headbox proper. The stock stream is agitated, at points therealong, to constitute a confined, relatively high energy or high velocity flowing stream and, at other points therealong, a slowed down or decelerated flowing stream, the flow conditions being so controlled as to cause delivery of the stock stream at the forming area at a predetermined velocity and with an avoidance of flocculation and a minimization of eddy currents and other non-uniform flow characteristics.

Stock flowed in a straight run tends to flock together and to clump, leading to unsightly streaked and hard-tomanage formations. Corrections of such objectionabl tendencies is achieved herewith by the means for interrupting the fibers in the respect that the velocity of the stock is significantly decreased and increased in seriatim manner at spaced points along its passage, thereby preventing settling out or separation of fiber bundles and the development of uneven stock conditions. High velocities are reduced to moderate velocities preparatory to flow onto the mold and without loss of the requisite fiber dispersion to produce the random directionality of the fibers so essential to satisfactory felting. The fibrous component of the stock is evenely dispersed and uniformly conditioned for laying down upon the mold, free of those local turbulences which cause non-uniformities in weight, thickness, and product appearance.

As another refinement of the invention, I provide dam means, each of which may be adjustably regulated vertically relative to and within a side pocket at one side of the apparatus Wherewith to control the level of the white water within the vat and in turn to control the level of the white water within the mold thereby reducing the differential in the hydrostatic head.

Sheet structure in papermaking is defined in terms of distribution of suspended colloidal and solid material, degree of fiber orientation, and degree of fiber flocculation throughout the sheet thickness.

With respect to fiber orientation, same is generally dependent on the relative speed between the forming surface and the fiber. The fibers are dragged with the mold in machine direction, the relative movement being the major cause of fiber orientation, although fibers within the stock while in motion normally exhibit a degree of initial orientation capable of adding to the during-formation development. By adjusting the stock fiow velocity through the correct positioning of the pond regulator, pronounced fiber orientation can be avoided and random formation with a good Squareness characteristic can be obtained.

Tendency to flocculate is an ever present stock characteristic. Stock concentration, turbulence within the stock, and time are significant factors affecting flocculation degree.

The physical characteristics of the formed web are largely determined by the rate at which stock flows relative to the speed of the forming surface and by the direc tion of stock flow relative thereto.

Formation of a good quality sheet dictates several desirable controlled conditions within a vat. There must be a steady stock feed and without the stock velocity becoming so slow as to aggravate the possibility of fiber flocculation, and yet not reaching the point of wild flow, thereby to set up eddy currents, a consistent factor in poor formation. Also, there must be close control of stock consistency. As consistency changes, the degrees of friction also influence flow characteristics. Low consistencies normally aid in improving formation, but only if the vat system is capable of handling increased volumes. Too often, flow systems are not sized properly and major adjustments in flows result in damaging the formed sheet.

The invention will be better understood from a consideration of the following detailed description of a preferred form of installation to be read in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side elevational view of the apparatus with the side pocket on the tending side removed for purposes of clarity and with certain parts being shown in section;

FIG. 2 is a view, in side elevation, of the tending side of the apparatus shown in FIG. 1 to better illustrate the relationship of the side pocket on said tending side to the remainder of the construction, said side pocket being shown in section in solid lines and the balance of the apparatus being shown in dash lines for purposes of clarity; and

FIG. 3 is a fragmentary elevational view from inside of the vat and the side pocket on the tending side of the apparatus looking toward the mold and the dam and the front end wall of the vat.

The machine includes a pair of vertically-extending, transversely-spaced side walls 2, a bottom wall 4, and a pair of vertically-extending, transversely-spaced end walls in the form of a front end wall 6 and a rear end wall 8, all interconnected as by weldments in known manner to define a walled vat seatable upon a foundation F.

Side walls 2 are each provided with an open-topped slot 10 extending downwardly from the top planar surface thereof and terminating in a rounded bottom, in which slot a removable wall 12 is mounted and secured to its respective side wall as by suitable bolting in a slot-closing relationship. Each wall 12 is apertured so as to mount a packing ring 14. A bearing means 16 in a bearing housing 17 rotatably supports the respective end of a shaft 18 of a mold disposed within the vat between the side walls. Said bearing means on each side of the machine is supported upwardly by a top wall of a side pocket subsequently to be described. For purposes of clarity, the side pocket is not shown in FIG. 1.

Mold 20 comprises a spoked cylindrical wire covered arrangement of conventional design, is disposed in a horizontally-extending manner so as to be located between vat side walls 2, and is rotatably mounted for rotation on its horizontal axis by a suitable drive means coupled to shaft 18 at the drive side of the apparatus.

Conventional outside deckles 21 may be provided at opposite sides of the vat for the usual purpose.

Each vat side wall 2 is provided with an opening 22 therethrough which serves to allow certain of the white water to pass from the vat and into the adjacent side pocket communicating with said opening.

Vertically above each such opening 22, another opening 24 of generally segment shape is provided in each vat side wall for purposes of allowing additional white water, in the case of back up, to pass from the inside of the mold within the vat and into the adjacent side pocket communicating with said opening.

A pickup felt 28 of conventional endless form is passed between the mold periphery upwardly of the vat and a couch roll 29 (desirably a plain roll, but conceivably in the form of a suction roll) disposed in nip-defining position adjacent the mold for the well-known pickup function as pressure is exerted upon the couch roll to cause it to bear upon the felt thereby to force the felt into contacting embracement with the mold thereby to remove the formed web of fibers from the mold periphery.

A shaft 30 of the couch roll is journalled at each of its opposite ends in a respective downwardly-depending bearing housing 31 carried by a respective couch arm 32 pivotally mounted at 34 on a respective stand 36 mounted on and extending upwardly from the respective vat side wall. The couch arms of the pair thereof are activated unisonly into and out of a desired couching position by means of a pair of air-loaded cylinders 38, each pivotally mounted at 40 upon the respective couch arm with its coacting piston rod 42 extending downwardly therefrom and pivotally engaged at 44 with its respective stand, the power means for energizing the cylinders being conventional and not being shown.

A headbox or pond, generally indicated by 50, is disposed within the vat adjacent the upward path of rotation 'of mold 20 (indicated by arrow 11) at one side of its vertical axial plane.

Headbox is formed by those portions of vat side walls 2 extending rearwardly from mold 20, rear end wall 8, the arcuate peripheral surface of the mold constituting the so-called upper forward pond wall, and a vertically-disposed, transversely-extending lower wall 52 which depends downwardly away from the mold and merges with an inclined rearwardly-facing transverselyextending lower wall 54. Side walls 2 are connected in headbox-defining manner to the respective adjacent edges of lower walls 52 and 54 on opposite sides of the headbox.

A vertically-disposed apron 56 mounts upon the upper face of lower wall 52 from side wall 2 to side wall 2 and may be adjustably secured relative to said lower wall as by a locking bar 58 secured to said lower wall by suitable means. The apron supports an upwardly-extending flexible sealing lip 60 disposed parallel to the mold axis for bearing upon the mold peripheral surface to provide an adjustable fluid-tight sealing means at the point of entry of the mold surface into the headbox area and thereby to aid the discharge of stock onto the mold, to seal off the area of the mold therebelow and the area of the vat below said mold, to preclude unwanted leakage of stock from the approach chamber, and to provide a smooth, continuous floor-line for the fluent stock flowing upwardly of lower wall 52. The sealing lip 60 mounted in the apron 56 can be removed to the front side of the machine or alley by opening a cover, not shown, in the side wall of the vat and by sliding the assembly out of the locking bar 58.

Headbox 50 communicates with a flow spreader, generally indicated by numeral 66, by which stock is supplied thereto through a vertically-disposed stock delivery or manifold inlet 68 from a connected underfeed stock supply conduit 70 through which the stock is delivered from a supply source (not shown) under force of suitable pumping means (not shown). If desired, a plurality of such manifold inlets 68 spaced transversely of the machine width may be provided for feeding at their upper extremities into a laterally-extending, circular-incross-section, inlet header or feed distribution tube 72 which, being closed at its opposite ends, extends across the machine width in a plane below the plane of the central horizontal axis of the mold, and has a cross section greatly in excess of the cross section of the manifold inlet or inlets so that, as stock is discharged upwardly thereinto, a decelerating action is realized. The violent vortex flow within the manifold inlet under a predetermined inlet pressure cascades into the inlet header and is slowed down in compensation for the reduced volume of stock relative to the area.

Being circular in cross section, the inlet header allows the stock to flow upwardly toward its topmost wall portion, there to be deflected tangentially into a communicating blending or primary approach chamber 76 illustratively defined by lower wall 54, the outboard end of which is connected to the lower side of a transverselyextending mouth in the side wall of the inlet header, and by a generally horizontally-extending lowermost wall portion 78 of rear wall 8 spaced upwardly of lower wall 54 and having an outboard end tangentially related and connecting to the upper side of the mouth.

Primary approach passage 76 defines a tapered passageway narrowing into a restricted orifice: at its mouth at its inboard end and extending transversely-coextensive with the machine width so as to provide substantially similar velocity and pressure conditions therealong.

Stock flowing vertically in the inlet header is impinged against the roof or deflecting wall defined by the top most wall portion of the inlet header and wall portion 78 of the primary approach passage so as to be deflected right angularly into a horizontal component of flow laterally through the primary approach passage. That is, in this passage, the stock undergoes a change of direction of at least so as to insure non-persistence of the velocities established into the inlet header and further to insure that the stock and the velocity energies thereof are blended in a desirably uniform equality across the machine width.

As the stock exited from the manifold inlet into the inlet header of larger cross section undergoes deceleration and pressure drop, so that stock as it exits from the inlet header and passes through the restricted primary approach passage undergoes acceleration, in a condition of fine scale turbulence and uniform dispersion uniformly across the machine width.

The so-accelerated stock is spouted from the throat of the primary approach passage as a high velocity stream into a vertically-extending secondary approach passage 82 defined by lower wall 52 and a spaced parallel wall portion 84 of rear end wall 8 and communicating with primary approach passage 76 at the throat. Stock existing through that throat is impinged against lower wall 52 so as to be once again deflected right angularly.

Secondary approach passage 82 being of a uniform width greater than the vertical dimension of the throat, it provides another deceleration chamber transversely-coextensive with the machine width for accommodating a relatively slow upward flow of stock upwardly for exiting into the headbox with which it communicates.

A rotatable rectifier roll or perforated holey roll 86, having the customary rectifier design and function and driven by suitable means (not shown), is preferentially transversely-disposed within the secondary approach passage and may be journalled in the opposite side walls 2 so as to be extendable'across the passage in close running relationship to the adjacent walls thereof where it will bridge the stock flowing therethrough to further induce turbulence and effectuate uniform intermingling of the stock fibers and elimination of accumulations of fiber bundles.

Thus the serpentine stock flow path through the approach-flow system is first vertically and upwardly, then defines a right angular turn into and through a primary approach passage of diminishing cross sectional area, and then defines a second right angular turn into a secondary approach passage allowing proportional decreases in flow rate as the point of emergency therefrom and into the headbox is approached.

While in this embodiment only two passages are shown, it will be understood that any number of passages may be provided and arranged for achieving successive phases of acceleration and deceleration with a desirable degree of friction losses, thereby damping undesirable pulsations in stock flow delivery and uniformly dispersing and directing distribution over the machine width. With such distributor means, the stock enters the forming area in the live condition considered so essential by papermakers, but with a complete absence of the boiling and rolling characteristics which lead to undesirable irregularities in the product.

With headbox 50, a pond or stock regulator is disposed and may comprise a pair of transversely-spaced verticallyextending side walls 92, each substantially contiguous with the inner side of its respective adjacent side wall 2, and transversely-extending forward and rearward walls 94 and 96 respectively connected thereto at opposite sides thereof, which forward and rearward walls are interconnected by a bottom wall 98 in a location substantially vertically offset from and rearwardly of and spaced above the secondary flow passage exit, said side and forward and rearward walls being interconnected by a generally horizontally-disposed top wall 100. Forward wall 94 is suit ably arcuately configured to conform generally to and to complement the contour of the adjacent mold 20.

The pond regulator may be motivated relative to the headbox in horizontal forward and rearward directions lengthwise of and relative to the mold by an adjusting means (not shown) mounted on one of the side walls 2. Thereby, wall 94- may be adjust-ed to any desired position relative to the adjacent quadrant of the mold so as to effectively control the cross-sectional area of an approach chamber or throat 104 defined by sealing lip 60 and apron 56, the forward wall 94 of the pond regulator, and the adjacent mold quadrant, all between opposite side walls 2.

Through such approach chamber or throat, the flow of stock is directed generally upwardly through the headbox from the exit of secondary flow passage 82 to impinge upon the adjacent arcuate segment of the cylindrical forming surface provided by the mold.

As will appear, the upper terminus of the approach chamber is in a plane above the level of the white water within the mold so that the entirety of the web formation takes place thereabove.

The pond regulator and a cooperant vertically-adjustable overflow dam or gate 108 mounted thereon and extending upwardly therefrom provide walls for defining the pond within the headbox whereby the stock may be maintained at a level denoted by L sufiicient to produce the required static and velocity head for web formation.

Overflow dam 108 accommodates the overflow of stock in excess of the amount which the mold forming surface is capable of receiving so that rearwardly of the pond such excess flows into a vertically-disposed excess stock overflow chamber 116 spaced rearwardly of and 8 parallel to pond regulator wall 96 and defined by stepped vertical wall portions 112 and 114 of rear end Wall '8. A drain sump 118 leads therefrom for recirculating excess stock back to the conventional fan pump.

Anelongated, vertically-disposed, transversely-extending sealing member 120 is fixed t0 and extends through rear end wall 8 so as, first, to extend upwardly therefrom into the headbox and toward pond regulator wall 98 in manner to maintain an adjustable seal thereat so as to effectuate a pressure within approach passage 104 by closing off the so-called heel area within the headbox and rearwardly of the pond regulator, while simultaneously allowing any desired adjustment of the pond regulator, and second, to regulate the quantity of back recirculation when not pressurized. That is, sealing member 120 defines a closed stock receiving chamber so that pressure may be built up within the approach passage merely by the action of the generated forces within the stock flow pump and without the introduction of any pressurized air to the assemblage.

The dimensioning of the cross sectional area of the approach passage, prior to and during formation, may be variably controlled, to allow a precise stock control at the forming area, by the adjustment of the pond regulator so as to move wall 94 toward or away from the mold, thereby to close or open throat 104.

Pressure is maintained within the approach passage by bringing the leading edge of the pond regulator into close proximity with the mold surface, it being envisioned that it might be brought to as close as .005 therefrom. The closer the edge, the greater the pressure which might be applied to the mold in the forming area, such application of pressure serving to induce a greater drainage in said forming area. Thereby, a more dilute stock might be used, or a heavier sheet might be formed, than would otherwise be possible.

The liquid portion of the stock or White Water flows through the wire mesh of the mold and interiorly of the mold and flows outwardly therefrom in the directions indicated by the arrows b and 0 generally opposite to the forming surface.

By draining or removing the white water from a side of the mold, as contrasted with discharge exclusively through the ends thereof, the level of the white water within the mold is essentially uniform across the mold width to result in a uniform flow of liquid or white water into the mold across the machine width and a corresponding formation of a web of uniform weight on the mold likewise across the machine. By flowing the major amount of the white water in generally radial directions, rather than axially, the gradient from the center of the mold to the ends thereof is essentially entirely eliminated.

Within the vat, an incliined wall extends from front end wall 6 to bottom Wall 4 and an inclined wall 132 extends from locking bar 58 to the bottom wall, each inciined wall terminating adjacent and on opposite sides of an opening 134 in said bottom wall, which said opening extends transversely of the vat from side wall to side wall thereof.

Said opening 134 communicates with a white water collecting pan 136 coextensive with the vat width, disposed below the plane of bottom wall 4, and being coupledat its center for fluid communication with a conduit 138 leading to a conventional fan pum (not shown).

The cascading or radially discharging white water moving in the general direction indicated by arrows b and c may be received on the stock-free or dry side of lower vat wall 52 as by the free-fall drainage area bottomed by the white water collecting pan. The normal level of the white water in the vat will be at the level indicated by the dash line WW1 in FIG. 1. As will hereafter appear, this level may be raised to a level such as indicated by the dash line WW2 by a means to be described.

A side pocket is provided on each side of the machine and each is generally L shaped in configuration.

With reference to FIGS. 2 and 3, the side pocket on the tending side of the apparatus is now described.

Said side pocket is defined by an inner 'wall constituted by the respective vat side Wall 2 and an outer wall 140 spaced therefrom and in parallelism with said side wall, a front end wall 142, a lower rear end wall 144, an upper rear end wall 146 a lower top wall 148 connecting walls 144 and 146 and an upper top wall 151 connecting walls 146 and 142 to form an enclosure seated upon a footing or bottom wall 150.

The upwardly facing surface of lower top wall 148 provides a support for respective bearing housing 17.

The side pockets of the pair function unisonly to receive excess white water from within the vat as determined by an adjustable gate or overflow dam 154 Which is vertically disposed within each side pocket. Said dam is shown in solid lines at a position of adjustment which allows the white water level WW1 Within the vat and a similar white water level WW1 in each side pocket.

There being a constant excess of such white water, within the vat, portions thereof flow through the openings 22 in the opposite side walls 2 and into the side pocket.

In the event of any backup of white water Within the vat, the secondary opening 24 also serves for the charge of excess white water therethrough from the vat and into the respective side pocket.

Vertically adjustable dam 154 maintains a desired white water level within the respective side pocket and Within the vat and serves to spill the excess white water into a side pocket compartment 156 forwardly of the dam and thence outwardly into a conduit 158 common to both side pockets and extending transversely of the vat and below inclined wall 130 and thence outwardly of conduit 158 through a centrally-disposed connecting conduit 160 leading to the white water storage chest, not shown.

If the overflow dam is raised, for example to the position shown in dash lines in FIG. 2, then the level inside the side pocket rises to the level mark WW2 and the level inside of the vat and ultimately inside of the mold rises to the same level marked WW2 in FIG. 1.

With the dam so adjusted, opening 24 serves as a discharge opening for the white water from the inside of the cylinder mold directly into the respectively side pocket. Opening 24 will thus be appreciated as being especially useful when operating with higher white water levels.

In this way, the machine can be operated with a white water level WW2 thereby reducing the differential in the hydrostatic head. This simulates the orthodox method of operation in the respect that there is only a small pressure drop between the outside and inside of the mold.

I claim:

1. In a papermaking machine, the combination of a vat comprising side and end walls, a cylinder mold disposed between and rotatably supported by said side Walls, curvate means radially spaced from the cylinder mold and defining cooperantly therewith a stock flow channel, means for adjusting the curvate means for essentially restricting the channel, means for discharging the stock flow through the channel whereby fibers thereof are deposited on the cylinder mold at one side thereof and liquid thereof flows into the mold and through the opposite side thereof and into the vat, means defining an enclosed side pocket formed on each of the side Walls of the vat, the side walls of the vat having openings communicating with the side pockets to permit the liquid to flow from the vat into the side pockets and discharge means leading from the side pockets to drain the liquid therefrom.

2. In a papermaking machine according to claim 1 including a dam in each said side pocket to control the level of the liquid within the vat and in turn to control the level of the liquid within the mold thereby reducing the differential in the hydrostatic head.

3. In a papermaking machine according to claim 1 including a primary stock approach passage connecting with and disposed substantially at right angles to the stock flow channel, said primary stock approach passage defining a tapered passageway narrowing into a restricted orifice at its point of connection with the stock flow channel.

4. In a papermaking machine according to claim 3 including a rectifier roll rotatably mounted in the stock flow channel and bridging the stock flow.

5. In a papermaking machine, the combination of a pulp vat or box comprising side and end walls, a cylinder mold disposed between and rotatably supported by said side walls, means defining 'white water gravity outlets in the side walls opening to the interior of the cylinder mold, means defining a stock inlet in. one of the end walls at one side of the cylinder mold, means defining a white water overflow box fixed to each vat side wall, and dam means in each overflow box for controlling the White water level within the vat.

6. In a cylinder type of paper machine, in combination, a vat for a pond of fibrous stock, a foraminous cylinder rotatably mounted therein, means defining stock overflow boxes on both sides of said vat, said vat having openings therein communicating with the stock overflow boxes, discharge conduits in said vat and in said stock overflow boxes and dam means in said stock overflow boxes for controlling the stock level in said vat.

References Cited UNITED STATES PATENTS 2/1957 Joslyn 162321 6/1965 Beachler 162-264 

1. IN A PAPERMAKING MACHINE, THE COMBINATION OF A VAT COMPRISING SIDE AND END WALLS, A CYLINDER MOLD DISPOSED BETWEEN AND ROTATABLY SUPPORTED BY SAID SIDE WALLS, CURVATE MEANS RADIALLY SPACED FROM THE CYLINDER MOLD AND DEFINING COPPERANTLY THEREWITH A STOCK FLOW CHANNEL, MEANS FOR ADJUSTING THE CURVATE MEANS FOR ESSENTIALLY RESTRICTING THE CHANNEL, MEANS FOR DISCHARGING THE STOCK FLOW THROUGH THE CHANNEL WHEREBY FIBERS THEREOF ARE DEPOSITED ON THE CYLINDER MOLD AT ONE SIDE THEREOF AND LIQUID THEREOF FLOWS INTO THE MOLD AND THROUGH THE OPPOSITE SIDE THEREOF AND INTO THE VAT, MEANS DEFINING AN ENCLOSED SIDE POCKET FORMED ON EACH OF THE SIDE WALLS OF THE VAT THE SIDE WALLS OF THE VAT HAVING OPENINGS COMMUNICATING WITH THE SIDE POCKETS TO PERMIT THE LIQUID TO FLOW FROM THE VAT INTO THE SIDE POCKETS AND DISCHARGE MEANS LEADING FROM THE SIDE POCKET TO DRAIN THE LIQUID THEREFROM. 